Floating caliper disc brake

ABSTRACT

An object of the present invention is to provide a floating caliper type disc brake which can effectively suppress the occurrence of uneven wear in linings of respective pads, and effectively suppress the occurrence of noise and judder during braking. In the present invention, a caliper is supported by a support member displaceably in an axial direction of a rotor. Pressed-side shim plates are respectively lined on reverse surfaces of back plates of pads supported by the support, while supporting-side shim plates are lined on an inner side surface of a claw portion and on a distal end face of a piston. The pressed-side shim plates and the pressing-side shim plates are respectively retained by mating members to be lined on by means of resilient retainers, and one surface of each of the mutually opposing pressed-side shim plates and one surface of each of the pressing-side shim plates are slidably abutted against each other.

TECHNICAL FIELD

A floating caliper type disc brake in accordance with the presentinvention is used for braking an automobile. The present invention isaimed at preventing uneven wear of pads incorporated in such a discbrake and uneven wear of a rotor with respect to its radial direction.

BACKGROUND ART

As disclosed in patent documents 1 to 3, as a disc brake for braking anautomobile, a floating caliper type in which a caliper is supporteddisplaceably by a support member by means of a pair of guide pins isconventionally widely known and is actually used extensively. FIGS. 21and 22 show a disc brake disclosed in the patent document 1 among suchfloating caliper type disc brakes. In this floating caliper type discbrake, during braking, a caliper 2 is displaced with respect to a rotor1 which rotates with a wheel (not shown). In the state in which the discbrake is assembled to a vehicle, a support member 3 provided in a stateof being disposed adjacent to one side of this rotor 1 is fixed to avehicle body (not shown) by means of mounting holes 4. In addition, thecaliper 2 is supported by this support member 3 displaceably in theaxial direction of the rotor 1.

For this reason, a pair of guide pins 5 are respectively provided inboth end portions of the caliper 2 as viewed in the rotating directionof the rotor 1, while a pair of guide holes 6 are similarly provided inboth end portions of the support member 3 of the support. The pair ofguide pins 5 and the pair of guide holes 6 are provided in parallel to acenter axis of the rotor 1. The guide pins 5 are inserted in the guideholes 6 slidably in the axial direction. A dust proof boot 7 is providedbetween an outer peripheral surface of a proximal end portion of eachguide pin 5 and an opening portion of each guide hole 6. It should benoted that there are cases where the inside diameters of the guide holes6 are mutually different, and there are cases where the outsidediameters of the guide pins 5 are also mutually differentcorrespondingly.

In addition, run-in side and run-out side engaging portions 8 and 9 arerespectively provided in both end portion of the support member 3 atpositions spaced apart in the circumferential direction of the rotor 1.Distal ends of these engaging portions 8 and 9 are bent in a U-shape insuch a manner as to straddle an outer peripheral portion of the rotor 1vertically in FIG. 21. Both end portions of a pair of back plates 11making up pads 10 a and 10 b are engaged with both these engagingportions 8 and 9 slidably in the axial direction of the rotor 1. Thecaliper 2 is disposed which has a cylinder portion 12 and a claw portion13 which are coupled by a bridge portion straddling the pads 10 a and 10b. A piston 14 for pressing the inner pad 10 a (the inner side in thetransverse direction of the vehicle, i.e., the lower side in FIG. 21)against the rotor 1 is liquid-tightly fitted in the cylinder portion 12of this caliper 2.

In effecting braking, pressure oil is fed into the cylinder portion 12to cause a lining 15 of the inner pad 10 a to be pressed against aninner side surface of the rotor 1 upwardly from below in FIG. 21 by thepiston 14. Then, as a reaction of this pressing force, the caliper 2 isdisplaced downwardly in FIG. 21 on the basis of the sliding motion ofthe guide pins 5 relative to the guide holes 6. Consequently, the clawportion 13 presses the lining 15 of the outer pad 10 b (the outer sidein the transverse direction of the vehicle, i.e., the upper side in FIG.21) against an outer side surface of the rotor 1. As a result, thisrotor 1 is firmly clamped from both inner and outer sides thereof,thereby effecting braking.

In addition, although not shown in FIGS. 21 and 22, a structure in whicha shim plate is clamped only on one side either between a reversesurface of the back plate 11 of the inner pad 10 a and a distal end faceof the piston 14 or between a reverse surface of the back plate 11 ofthe outer pad 10 b and an inner side surface of the claw portion 13, isconventionally widely known through disclosures in patent documents 2,5, and 7 to 10. In addition, a structure in which shim plates arerespectively clamped between mating ones of the aforementioned surfacesis also conventionally known through disclosures in patent documents 3,4, and 6. With the structures disclosed in these patent documents, byproviding the shim plates between the mating ones of the surfaces (orbetween one pair of surfaces), there are possibilities of reducing brakenoise and judder occurring during braking and of alleviating the degreeto which the torque transmitted from the rotor 2 to the pads 10 a and 10b is transmitted to the caliper 3.

It should be noted that as prior art documents concerning the presentinvention, patent documents 11 and 12 are known in addition to thepatent documents 1 to 10.

-   -   [Patent Document 1] JP-A-55-123029    -   [Patent Document 2] JP-A-11-044331    -   [Patent Document 3] JP-Y-2596090    -   [Patent Document 4] JP-A-59-019730    -   [Patent Document 5] JP-A-08-093808    -   [Patent Document 6] JP-A-10-318301    -   [Patent Document 7] JP-U-57-149331    -   [Patent Document 8] JP-U-02-124330    -   [Patent Document 9] JP-U-03-124031    -   [Patent Document 10] JP-U-05-042779    -   [Patent Document 11] JP-U-62-069635    -   [Patent Document 12] JP-A-55-014381

In the case of the floating caliper type disc brake which isconventionally known, as shown in FIGS. 21 and 22, and is constructedand operates as described above, there are cases where so-called unevenwear occurs in which the amounts of wear of the linings 15 of the pads10 a and 10 b become non-uniform. The occurrence of this uneven wearconstitutes a cause of the occurrence of brake noise and judder duringbraking. A detailed description will be given of this aspect withreference to FIG. 23. It should be noted that although the structure ofdetailed portions differs between the structure shown in FIGS. 21 and 22and the structure shown in FIG. 23, the basic structures are the same.

In the state in which the rotor 1 has rotated in the direction indicatedby arrow A in FIG. 23, if the linings 15 of the pads 10 a and 10 b arepressed against both side surfaces of this rotor 1 to effect braking, adrag force F₁ acts upon each of the linings 15 as the reaction of thebraking force applied to this rotor 1. Further, forces F₂ and F₃ actingin the same direction as the drag force F₁ are respectively applied fromthe back plates 11 of the pads 10 a and 10 b to the inner side surface(the lower surface in FIG. 23) of the claw portion 13 of the caliper 2and the distal end face (the upper end surface in FIG. 23) of the piston14. In this case, there are cases where the caliper 2 tends to rotateclockwise in the drawing about an engaging portion o between the guidehole 6 and the guide pin 5 on the run-in side (the left-hand side inFIG. 23) of the rotor 1. Further, there are cases where moments M₁ andM₂ about the engaging portion o respectively act upon the claw portion13 and the piston 14 on the basis of the forces F₂ and F₃. In addition,the length L₁ between the engaging portion o and the portion of contactbetween the inner side surface of this claw portion 13 and the backplate 11 of the outer pad 10 b is greater than the length L₂ betweenthis engaging portion o and the portion of contact between the distalend face of the piston 14 and the back plate 11 of the inner pad 10 a(L₁>L₂). For this reason, of the moments M₁ and M₂, the moment M₁ actingupon the claw portion 13 becomes greater than the moment M₂ acting uponthe piston 14 (M₁>M₂).

Meanwhile, in the case of the conventional structure shown in FIGS. 21and 22 referred to above, the inner side surface of the claw portion 13and the distal end face of the piston 14 are in direct contact with theback plates 11 of the respective pads 10 a and 10 b. For this reason,the frictional force acting between each of these back plates 11 andeach of the inner side surface of the claw portion 13 and the distal endface of the piston 14 become large. Accordingly, the moments M₁ and M₂become large, and the caliper 2 is likely to tilt substantially withrespect to the planar direction of the rotor 1 (is likely to undergobody tilting). In the case where the caliper 2 has tilted in thismanner, the amounts of wear of the linings 15 of the pads 10 a and 10 bbecome non-uniform with respect to the rotating direction A of the rotor1. Specifically, as for the outer pad 10 b, the wear on the run-out side(the right-hand side in FIG. 23) of the rotor 1 progresses (the amountof wear becomes large) in comparison with the wear on the run-in side ofthe rotor 1. On the other hand, as for the inner pad 10 a, the wear onthe run-in side of the rotor 1 progresses in comparison with the wear onthe run-out side of the rotor 1. As a result, uneven wear occurs in thelinings 11 of the pads 10 a and 10 b.

In contrast, in the case of the structures disclosed in the patentdocuments 2, 5, and 7 to 10, the shim plate is clamped only on one sideeither between the reverse surface of the back plate 11 of the inner pad10 a and the distal end face of the piston 14 or between the reversesurface of the back plate 11 of the outer pad 10 b and the inner sidesurface of the claw portion 13. For this reason, there is a possibilitythat the frictional force acting in one these two pairs of surfaces canbe made small, so that the force F₂ (or outer peripheral surface)applied to the claw portion 13 or the piston 14 can be made small, andone of the moments M₁ and M₂ can be made small. However, in the case ofthe structures disclosed in the patent documents 2, 5, and 7 to 10, theshim plates are clamped not on both sides between the reverse surface ofthe back plate 11 of the inner pad 10 a and the distal end face of thepiston 14 and between the reverse surface of the back plate 11 of theouter pad 10 b and the inner side surface of the claw portion 13. Forthis reason, of the moments M₁ and M₂, the other moment remains stilllarge, and the effect whereby the tilting of the caliper 2 duringbraking can be suppressed is low.

In contrast, in the case of the structures disclosed in the patentdocuments 3, 4, and 6, the shim plates are respectively clamped on bothsides between the reverse surface of the back plate 11 of the inner pad10 a and the distal end face of the piston 14 and between the reversesurface of the back plate 11 of the outer pad 10 b and the inner sidesurface of the claw portion 13. However, in the case of the structuresdisclosed in the patent documents 3, 4, and 6, the following drawbacksare encountered, respectively. First, in the case of the structuredisclosed in the patent document 3, the shim plates are respectivelyinstalled on one sides of the back plates 11 of both inner and outerpads 10 a and 10 b, and relative displacement of these shim plates ismade possible in predetermined ranges with respect to the respectiveback plates 11 in the rotating direction and the radial direction of therotor 1. However, the side surface of each of these shim plates on theside of the claw portion 13 or the piston 14 is directly opposed(without via the shim plate) to the inner side surface of this clawportion 13 or the distal end face of the piston 14. In addition, in thecase of the structure disclosed in the patent document 4, a thin plateformed by securing a vibration isolating member between two shim platesis provided between each of the reverse surfaces of the back plates 11of both inner and outer pads 10 a and 10 b and each of the inner sidesurface of the claw portion 13 and the distal end face of the piston 14.In the case of such a structure disclosed in the patent documents 3 and4, the moments M₁ and M₂ acting upon the claw portion 13 and the piston14 cannot be made sufficiently small, and the effect of making itpossible to suppress the tilting of the caliper 2 during braking issmall.

In the case of the structure disclosed in the patent document 6, aninner shim plate and an outer shim plate are provided between each ofthe reverse surfaces of the back plates 11 of both inner and outer pads10 a and 10 b and each of the inner side surface of the claw portion 13and the distal end face of the piston 14. Of these shim plates, theinner shim plates are fixed to the back plates 11 in a state in whichthe displacement of these shim plates in the rotational direction andthe radial direction of the rotor 1 is prevented. In addition, each ofthe outer shim plates is retained by each of the back plates 11 in sucha manner as to cover the adjacent inner shim plate, and the relativedisplacement of each of these outer shim plates with respect to each ofthe inner shim plates is made possible in a predetermined range in therotational direction of the rotor 1. For this reason, if the frictionalforce acting between each inner shim plate and each outer shim plate ismade small, there is a possibility of making it possible to suppress thetilting of the caliper 2 during braking. However, the range in whicheach outer shim plate is displaceable relative to each inner shim plateis limited, so that it is impossible to effectively obtain the effect ofpreventing the tilting of the caliper 2 during braking.

Meanwhile, in the case of the conventional structure shown in FIGS. 21and 22 referred to above, in addition to the problem that uneven wearoccurs in the above-described pads 10 a and 10 b, there is a problem inthat the amount of wear of the rotor 1 becomes non-uniform in the radialdirection, i.e., so-called uneven wear can occur. The cause of theoccurrence of such uneven wear in the radial direction of the rotor 1 isconceivably as follows: Namely, the rotor 1 during braking by the discbrake undergoes a temperature rise in consequence of the friction withthe linings 15 of the respective pads 10 a and 10 b. During thistemperature rise, the sliding portion of the rotor 1 provided inproximity to its outer periphery is deformed in the axial direction(specifically, outwardly) as shown by the chain lines in FIG. 24, duringhigh-temperature braking and immediately after braking, owing to theeffect of an axial offset between its mounting portion provided on theinside diameter side for the wheel and its sliding portion provided onthe outside diameter side for the pads 10 a and 10 b. Further, it hasbeen experimentally confirmed that a portion of the rotor 1 which isclamped by the pair of pads 10 a and 10 b during braking tilts withrespect to a phantom plane which is present in an orthogonal directionto the rotational center.

When the sliding portion of the rotor 1 tilts in this way, the linings15 of the pads 10 a and 10 b partially abut against both side surfacesof this rotor 1 during braking. Namely, in the case of the conventionalgeneral floating caliper type disc brake, the pair of guide pins 5 andthe pair of guide holes 6, to which these guide pins 5 are fitted, areengaged with each other only axially displaceably. Accordingly, theinner side surface of the claw portion 13 and the distal end face of thepiston which press the reverse surfaces of the back plates 11 of thepads 10 a and 10 b remain to be in the orthogonal direction to therotational center of the rotor 1. For this reason, the linings 15partially abut against both side surfaces of the rotor 1 in theabove-described manner, so that the rotor 1 is unevenly worn duringhigh-temperature braking or high-temperature idling. Specifically, inthe case of the outer side of this rotor 1, for example, the wear on theradially outward side progresses (the amount of wear increases) ascompared to the wear on the inward side. On the other hand, in the casethe inner side of this rotor 1, for example, the wear on the radiallyinward side progresses as compared to the wear on the outward side. Inwhichever direction uneven wear progresses, not only does the state ofsliding contact between each side surface of this rotor 1 and eachlining 15 become inappropriate in the state in which the rotor 1 has notbeen deformed, and the durability of the rotor 1 and both pads 10 a and10 b including the linings 15 unfavorably declines.

As disclosed in the patent document 2, there is an example in which aportion of the guide pin is loosely inserted in the guide hole. Withthis structure, however, a distal end portion of a main pin having asmall clearance with respect to a small-diameter portion becomesdeformed during braking, and causes a cylinder body to follow thecircumferential displacement of the rotor. For this reason, it isapprehended that the sliding resistance based on the deformation of thedistal end portion of the main pin becomes large.

The floating caliper type disc brake in accordance with the inventionhas been devised to overcome the above-described drawbacks.

DISCLOSURE OF THE INVENTION

In the same way as the above-described conventionally known floatingcaliper type disc brake, the floating caliper type disc brake inaccordance with the invention includes a support, a pair of pads, acaliper, and a piston.

Of these members, the support member is fixed to a vehicle body in sucha manner as to be disposed adjacent to a rotor which rotates togetherwith a wheel.

In addition, the pair of pads are supported by the support member onboth sides of the rotor slidably in an axial direction thereof.

In addition, the caliper is supported by the support member displaceablyin the axial direction of the rotor, the caliper being supported by aplurality of guide holes provided in the support member and a pluralityof guide pins respectively fitted in the guide holes.

In addition, of the claw portion and the piston, the claw portion isprovided on one side of a bridge portion of the caliper, while thepiston is provided on another side thereof, the bridge portionstraddling the rotor.

In addition, the pair of pads are pressed against both side surfaces ofthe rotor in consequence of the extension of the piston so as to effectbraking.

In the floating caliper type disc brake in accordance with theinvention, particularly in the floating caliper type disc brakeaccording to claim 1, pressed-side shim plates are respectively retainedby those surfaces (reverse surfaces) of back plates of the pair of padswhich are located away from a rotor side, pressing-side shim plates arerespectively retained by pressing sides of the claw portion and thepiston, and each of the pressed-side shim plates and each of thepressing-side shim plates are slidably abutted against each other.

In addition, in the floating caliper type disc brake according to claim9, pressed-side shim plates are respectively fixed to or retained bythose surfaces (reverse surfaces) of back plates of the pair of padswhich are located away from a rotor side, pressing-side shim plates arerespectively fixed to or retained by pressing sides of the claw portionand the piston (e.g., are respectively fixed to the pressing sides ofthe claw portion and the piston by bonding), and each of thepressed-side shim plates and each of the pressing-side shim plates areslidably abutted against each other.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially cutaway view, taken from an outside diameter side,of a floating caliper type disc brake in accordance with a firstreference example of the reference examples of the invention.

FIG. 2 is half side views illustrating three examples of the shape of aguide pin.

FIG. 3 is a schematic view, taken along line A-A in FIG. 1, of a statein which a caliper is swung and displaced in conjunction with thedeformation of a rotor.

FIG. 4 is a view illustrating a second reference example of thereference examples of the invention and similar to FIG. 1.

FIG. 5 is a diagram illustrating a first embodiment of the invention andcorresponding to the A-A cross section in FIG. 1.

FIG. 6 is an exploded view of a part B in FIG. 5.

FIG. 7 is an exploded view of a part C in FIG. 5.

FIG. 8 is a cross-sectional view for explaining an effect which isobtained when guide pins and guide holes are engaged with each otheronly axially displaceably in the first embodiment.

FIG. 9 is an enlarged cross-sectional view corresponding to a part D inFIG. 8, for explaining another effect which is obtained in accordancewith the first embodiment.

FIG. 10 is a graph in which results of an experiment conducted toconfirm the effects obtained by the invention are shown by therelationship between the oil pressure (braking fluid oil) of pressureoil fed into a cylinder during braking and the tilting angle of a centeraxis of the caliper.

FIG. 11 is an exploded perspective view of a piston, an inner pad, andinner pressing- and pressed-side shim plates for constituting a secondembodiment of the invention.

FIG. 12 is similarly an exploded perspective view of a claw portion, anouter pad, and outer pressing-and pressed-side shim plates.

FIG. 13 is a diagram illustrating a state of engagement between the clawportion and the outer pressing-side shim plate in accordance with thesecond embodiment.

FIG. 14 is a view illustrating a third embodiment of the invention andsimilar to FIG. 12.

FIG. 15 is a view illustrating a fourth embodiment of the invention andsimilar to FIG. 12.

FIG. 16 is a diagram similar to FIG. 13 and illustrating another shapeof a retaining protrusion formed on the pressing-side shim plate.

FIG. 17 is a view illustrating a fifth embodiment of the invention andsimilar to FIG. 11.

FIG. 18 is a view illustrating a sixth embodiment of the invention andsimilar to FIG. 11.

FIG. 19 is a substantially cross-sectional view, partly omitted, of aseventh embodiment of the invention.

FIG. 20 is an enlarged cross-sectional view corresponding to a part E inFIG. 19 and illustrating a state in which the claw portion has beenswung and displaced relative to the outer pressed-side shim plate andthe outer pad.

FIG. 21 is a partial cutaway view illustrating a state in which a firstexample of a conventional structure is viewed from the same direction asthat of FIG. 1.

FIG. 22 is a cross-sectional view taken along line F-F in FIG. 21.

FIG. 23 is a cross-sectional view for explaining moments acting upon theclaw portion and the piston of the caliper during braking.

FIG. 24 is a partial cross-sectional view illustrating a state in whichthe rotor is deformed due to a temperature rise accompanying thebraking.

In the drawings, the reference numbers, 1 is a rotor, 2 and 2 a arecalipers, 3 and 3 a are supports, 4 is a mounting hole, 5, 5 a, 5 b, 5c, 5 d, 5 e and 5 a′ are guide pins, 6, 6 a, 6 a′ are guide holes, 7, 7a and 7 a′ are boots, 8 and 8 a are run-in side engaging portion, 9 and9 a are run-out side engaging portion, 10 a and 10 b are pads, 11 is aback plate, 12 is a cylinder portion, 13 and 13 a are claw portions, 14is a piston, 15 is a lining, 16 is an arm portion, 17 is a through hole,18 is a bolt, 19 is a threaded hole, 20 a, 20 b, 20 c, 20 d and 20 a′are large-diameter portions, 21 is an inclined surface portion, 22 is acylindrical surface portion, 23 a, 23 b, 23 a′ and 23 b′ are rings, 24is a retaining stepped portion, 25 is a sleeve, 26 a and 26 b arepressed-side shim plates, 27 a and 27 b are pressing-side shim plates,28 a, 28 b, 28 a′ and 28 b′ are small-diameter portion, 29 is a extendedsmall-diameter portion, 30 is a retainer, 31 is an outside diameter-sideretainer, 32 is an inside diameter-side retainer, 33 a and 33 b areretaining grooves, 34 is a retainer, 35 is a recess, 36 is a pressingpiece, 37 is a curved portion, 38 is a bent piece, 39 is an insidediameter-side curved portion, 40 is an outside diameter-side curvedportion, 41 is a retaining protrusion, 42 is a retaining hole, 43 and 43a are retaining protrusion, 44 is a retaining protrusion, and 45 is aretaining protrusion.

BEST MODE FOR CARRYING OUT THE INVENTION

In implementing the invention, preferably as stated in claims 2 and 10,in the floating caliper type disc brake according to claim 1 or 9, eachof the plurality of guide pins has, at its each opposite end portion inthe axial direction of the rotor, a first diameter portion having aclearance of a predetermined dimension or more with respect to the guidehole in which the guide pin is fitted, and at least one of the guidepins has, in its intermediate portion in the axial direction of therotor, a second diameter portion whose diameter is larger than that ofthe first diameter portion.

In the case of this preferred construction, the plurality of pins forsupporting the caliper onto the support member have, at their axiallyopposite end portions, a clearance of a predetermined dimension or morewith respect to the guide hole, and swing about engaging portions eachprovided between an outer peripheral portion of the second diameterportion formed in at least one of the guide pins and an inner peripheralsurface of the guide hole in which that guide pin is inserted. For thisreason, even in cases where the rotor has been deformed in the axialdirection due to a temperature rise accompanying the braking, the innerside surface of the claw portion and the distal end face of the pistoncan be made parallel to both side surfaces of this rotor. As a result,the linings of the pair of pads are pressed against both side surfacesof the rotor substantially uniformly in areas ranging from the innerperipheral edge to the outer peripheral edge. Thus, it is possible toprevent the situation in which the rotor becomes partially worn due toits own displacement in the tilting direction, i.e., the amount of wearof the rotor is radially biased. Furthermore, according to thispreferred construction, it is possible to make much smaller the momentacting upon this caliper as a whole on the basis of the forces appliedto the caliper from the rotor during braking, and it is possible to moreeffectively suppress this caliper from tilting with respect to theplanar direction of the rotor. As a result, it is possible to moreeffectively suppress the occurrence of uneven wear in the linings of thepads, and more effectively suppress the brake noise and judder occurringduring braking.

FIRST REFERENCE EXAMPLE

FIGS. 1 to 3 show a first reference example of the invention. A floatingcaliper type disc brake of this reference example has a support member 3a, a pair of pads 10 a and 10 b, a caliper 2 a, a claw portion 13 a, anda piston 14 (see FIGS. 21 and 22). Of these members, the support member3 a is fixed to a vehicle body in such a manner as to be disposedadjacent to a rotor 1 which rotates together with the wheel. Inaddition, the pads 10 a and 10 b are respectively disposed on both sidesof the rotor 1 in a state which the pads 10 a and 10 b are supported bythe support member 3 a. It should be noted that the structures andaction of a portion for supporting this support member 3 a by thevehicle body, portions for supporting the pads 10 a and 10 b by thesupport member 3 a, and portions for pressing the pads 10 a and 10 bagainst both side surfaces of the rotor 1 by means of the claw portion13 a and the piston 14 are similar to those of conventionally widelyknown disc brakes, including the structure shown in FIGS. 21 and 22referred to above. Therefore, a detailed illustration and descriptionthereof will be omitted.

The caliper 2 a is supported by the support member 3 a displaceably inthe axial direction of the rotor 1 (in the vertical direction in FIG.1). For this reason, guide holes 6 a and 6 a′, which are open only onthe inner side, are respectively formed in the axial direction of therotor 1 inside a run-in side engaging portion 8 a and an run-out sideengaging portion 9 a which are provided in both end portions, as viewedin the circumferential direction of the rotor 1, of the support member 3a. In addition, proximal end portions of guide pins 5 a and 5 a′ arerespectively supported and fixed by distal end portions of a pair of armportions 16 formed at a portion (inner side end) of the caliper 2 a in astate of projecting in the circumferential direction of this rotor 1.Namely, as a pair of bolts 18, which are respectively inserted from theinner side into a pair of through holes 17 formed in the distal endportions of the arm portions 16, are threadedly engaged with andtightened in a pair of threaded holes 19 which are open in proximal endfaces of the guide pins 5 a and 5 a′, the proximal end portions of theguide pins 5 a and 5 a′ are supported and fixed by the distal endportions of the arm portions 16. It should be noted that although theinside diameters of the guide holes 6 a and 6 b and the outsidediameters (the outside diameters of large-diameter portions 20 a and 20a′, which will be described later, and portions which are present onaxially opposite sides of the large-diameter portions 20 a and 20 a′) ofthe guide pins 5 a and 5 a′, which are respectively provided as pairs,are illustrated as being identical, these diameters need not necessarilybe identical as in the case of the above-described conventionalstructure.

In the case of this example, as such guide pins 5 a and 5 a′ areinserted into the guide holes 6 a and 6 a′ from the inner side openings,the caliper 2 a is supported by the support member 3 a displaceably inthe axial direction (the vertical direction in FIG. 1) of the rotor 1.The guide pins 5 a and 5 a′ have solid bodies made of a metal, and thelarge-diameter portions 20 a and 20 a′ whose outside diameters aregreater than those of both end portions of these guide pins 5 a and 5 a′are respectively formed in axially intermediate portions of the guidepins 5 a and 5 a′. Outer peripheral surfaces of these large-diameterportions 20 a and 20 a′ and inner peripheral surfaces of the guide holes6 a and 6 a′ are engaged with each other axially slidably.

Of the guide pins 5 a and 5 a′, outside diameters d₂ of thelarge-diameter portions 20 a and 20 a′ are made slightly (e.g., by 0.2mm or less, preferably 0.15 mm or thereabouts) smaller than insidediameters D (in an ordinary sized vehicle or smaller, preferably 10 mmor thereabouts) of the guide holes 6 a and 6 a′ (D>d₂≧D−0.2 mm,preferably d₂=D−0.15 mm). Thus, these large-diameter portions 20 a and20 a′ are fitted into the guide holes 6 a and 6 a′ with a smallclearance in the radial direction and axially displaceably. In contrast,outside diameters d₁ of small-diameter portions 28 a, 28 b, 28 a′, and28 b′, which are remaining portions of the guide pins 5 a and 5 a′ andare axially offset from the large-diameter portions 20 a and 20 a′, aremade sufficiently (e.g., by 0.5 mm or more, preferably 0.62 mm orthereabouts) smaller than the inside diameters D of the guide holes 6 aand 6 a′ (d₁≦D−0.5 mm, preferably d₁=D−0.62 mm). Thus, the relevantportions are made slightly swingable and displaceable in the radialdirection inside the guide holes 6 a and 6 a′. It should be noted thatthe outside diameters d₁ of the small-diameter portions 28 a, 28 b, 28a′, and 28 b′are made slightly different depending on the relative sizeof the brake and the deformability of the rotor 1.

In addition, as the guide pins 5 a and 5 a′ respectively having thelarge-diameter portions 20 a and 20 a′ in the axially intermediateportions, FIGS. 1 and 2A show one in which the shape of a generatingline of this large-diameter portion 20 is trapezoidal. In such alarge-diameter portion 20, an axial length L₂₂ of a cylindrical surfaceportion 22 excluding inclined surface portions 21 at both ends is set tobe 10 to 20 mm or thereabouts, which is sufficiently (e.g., by ¼ orless) shorter than a length L_(5a) (e.g., 50 to 80 mm or thereabouts) ofthe portion of each of the guide pins 5 a and 5 a′ inserted in each ofthe guide holes 6 a and 6 a′ (L₂₂<<L_(5a)). In addition, the guide pins5 a and 5 a′ become swingable and displaceable about the large-diameterportions 20 a and 20 a′ in correspondence with very small gaps which areeach present between the outer peripheral surface of the cylindricalsurface portion 22 and the inner peripheral surface of each of the guideholes 6 a and 6 a′.

Further, elastic rings 23 a and 23 b, 23 a′ and 23 b′, made of rubber orthe like are fitted over the guide pins 5 a and 5 a′ at two axialpositions, i.e., at a distal end portion and a proximal end portion,where each of the large-diameter portions 20 a and 20 a′ is locatedtherebetween. Of these rings 23 a, 23 b, 23 a′, and 23 b′, the rings 23a and 23 a′ respectively fitted over the distal end portions of theguide pins 5 a and 5 a′ are formed into mere hollow cylindrical shapes,and are respectively fitted over and supported on small-diameterretaining stepped portions 24 formed at the distal end portions of theseguide pins 5 a and 5 a′. On the other hand, the rings 23 b and 23 b′fitted over the proximal end portions of these guide pins 5 a and 5 a′are formed integrally with dust-proof boots 7 a and 7 a′ respectivelyprovided between outer peripheral surfaces of the proximal end portionsof these guide pins 5 a and 5 a′ and the openings in the guide holes 6 aand 6 a′. Each of the rings 23 a and 23 b, 23 a′ and 23 b′, is providedin a radially elastically compressed state between the outer peripheralsurface of each of the guide pins 5 a and 5 a′ and the inner peripheralsurface of each of the guide holes 6 a and 6 a′.

With the floating caliper type disc brake of this reference exampleconstructed as described above, the caliper 2 a is swingable withrespect to the support member 3 a about engaging portions between theouter peripheral surfaces of the large-diameter portions 20 a and 20 a′of the guide pins 5 a and 5 a′ and the inner peripheral surfaces of theguide holes 6 a and 6 a′. For this reason, even in cases there the rotor1 has been axially deformed due to a temperature rise accompanying thebraking, as shown by the chain lines in FIG. 24 referred to above, theinner side surface of the claw portion 13 a and the distal end face ofthe piston 14 can be made parallel to both side surfaces of the rotor 1.Namely, as a result of the fact that the inner side surface of the clawportion 13 a and the distal end face of the piston 14 press the reversesurfaces of back plates 11 of the pads 10 a and 10 b, in a state inwhich linings 15 of the pads 10 a and 10 b are pressed against both sidesurfaces of the rotor 1, forces act upon the caliper 2 a in directionsin which the inner side surface of the claw portion 13 a and the distalend face of the piston 14 are set parallel to both side surfaces of therotor 1.

On the basis of these forces, the caliper 2 a is swung with respect tothe support member 3 a in the above-described manner. At this juncture,the rings 23 a and 23 b, 23 a′ and 23 b′, are radially elasticallycompressed between the outer peripheral surfaces of the guide pins 5 aand 5 a′ and the inner peripheral surfaces of the guide holes 6 a and 6a′. For this reason, the inner side surface of the claw portion 13 a andthe distal end face of the piston 14 become parallel to both sidesurfaces of the rotor 1. The linings 15 of the pads 10 a and 10 b arerespectively pressed against both side surfaces of this rotor 1substantially uniformly in areas ranging from their inner peripheraledges to their outer peripheral edges. As a result, it is possible toprevent the rotor 1 from becoming partially worn with respect to theradial direction owing to the tilting of the rotor 1 itself.

A description will be given of this aspect with reference to FIG. 3. Acase is considered in which the rotor 1 has tilted by an angle θ₁ towardthe outer side (the left-hand side in FIG. 3) in conjunction with atemperature increase occurring during braking. In this case as well, theguide hole 6 a provided in the support member 3 a supported by and fixedto the vehicle body side remains parallel to the rotational center ofthe rotor 1. On the other hand, the caliper 2 a provided with the clawportion 13 a and the piston 14 for pressing the pair of pads 10 a and 10b against both side surfaces of this rotor 1 is swung in the directionof following the tilting direction of the rotor 1 (counterclockwise inFIG. 3) owing to forces accompanying these pressing forces. Thisswinging motion is possible by the portion of an angle θ₂ until thedistal end portion or the proximal end portion of the guide pin 5 aabuts against the inner peripheral surface of the inner side surface 6a, while compressing circumferential portions of the pair of rings 23 aand 23 b about the large-diameter portion 20 a which is a portion of theguide pin 5 a. This swingable angle θ₂ can be adjusted by changing theoutside diameter of the remaining portion of the guide pin 5 a which isaxially offset from the large-diameter portion 20 a. Accordingly, if theoutside diameter of the portion axially offset from the large-diameterportion 20 a is adjusted in correspondence with the tilt angle θ₁ of therotor 1 determined experimentally, the linings 11 of the pads 10 a and10 b can be pressed uniformly against both side surfaces of this rotor 1by causing the inner side surface of the claw portion 13 a and thedistal end face of the piston to follow the inclination of the rotor 1.

Thus, in the case of the floating caliper type disc brake of thisreference example, by devising the shapes of the guide pins 5 a and 5a′, the caliper 2 a is supported by the support member 3 a slightlyswingably and displaceably. The guide pins 5 a and 5 a′ have solidbodies which are entirely fabricated of a hard metal such as stainlesssteel, and have sufficient strength and rigidity. Accordingly, it ispossible to sufficiently secure the supporting strength of the caliper 2a by the support member 3 a by means of the guide pins 5 a and 5 a′. Inaddition, the large-diameter portions 20 a and 20 a′ of the guide pins 5a and 5 a′ are fitted in the guide holes 6 a and 6 a′ with respect tothe radial direction. Further, the rings 23 a and 23 b, 23 a′ and 23 b′,are provided at positions sandwiching the large-diameter portions 20 aand 20 a′ from both sides in the axial direction in a state of beingelastically compressed in the radial direction. Accordingly, the caliper2 a becomes stable with respect to the support member 3 a, and it ispossible to reduce the rattling sound occurring during non-braking.

It should be noted that as the shape of the large-diameter portion ofthe guide pin for allowing the floating caliper type disc brake to beprovided with the above-described function, it is also possible to adoptthose shown in FIGS. 2(b) and 2(c), in addition to the one describedabove. Of these guide pins, a guide pin 5 b shown in FIG. 2(b) is formedsuch that a hollow cylindrical surface-shaped large-diameter portion 20b formed in an axially intermediate portion is sandwiched from its bothaxial sides by a pair of curved surfaces whose respective generatinglines are convex circular arcs having large radii of curvature, theportion which is inserted into the guide hole being thus formed in theshape of a beer barrel. Meanwhile, a guide pin 5 c shown in FIG. 2(c) isformed such that a hollow cylindrical sleeve 25 formed of a metal or ahard synthetic resin is fitted over and fixed to an axially intermediateportion, and an outer peripheral surface of this sleeve 25 is formed asa large-diameter portion 20 c. Furthermore, although not shown, theportion where the shape of the generating line is rectilinear may beomitted from the shape shown in FIG. 2(b), and the entire large-diameterportion may be formed into a curved surface where the shape of thegenerating line is a convex circular arc.

SECOND REFERENCE EXAMPLE

Next, FIG. 4 shows a second reference example of the invention. In thecase of this reference example, the large-diameter portion 20 a isformed only on one (run-in side) guide pin 5 a. In this case, theoutside diameter d₁ of a guide pin 5 d is made sufficiently smaller thanthe inside diameter D (in an ordinary sized vehicle or smaller,preferably 10 mm or thereabouts) of the guide hole 6 a′ into which thatguide pin 5 d is inserted over the entire length (d₁≦D−0.5 mm,preferably d₁=D−0.62 mm). Further, the rings 23 a′ and 23 b′ arerespectively provided between, on the one hand, two positions on theinner peripheral surface of the guide hole 6 a′ and, on the other hand,two positions on the outer peripheral surface of the mating guide pin 5d. This arrangement makes it possible to prevent the mating guide pin 5d from rattling inside the guide hole 6 a′ during non-braking. In thecase of this example, the portion which is an axially intermediateportion in the outer peripheral surface of the guide pin 5 d and islocated between the pair of small-diameter portions 28 a′ and 28 b′ isan extended small-diameter portion 29 serving as a fourth diameterportion stated in claim 4. It should be noted that the structure of thecombination of the guide pins and the guide holes may be changed betweenthe run-in side and the run-out side.

Embodiments First Embodiment

Next, a description will be given of a first embodiment of the inventionshown in FIGS. 5 to 7. In the case of this embodiment, in addition tothe structure of the above-described first reference example, a pair ofshim plates are provided between each of the pair of pads 10 a and 10 band each of the claw portion 13 a and the piston 14. The arrangementprovided is such that the braking torque applied to the pads 10 a and 10b due to the friction between each of the linings 15 of the pair of pads10 a and 10 b and each of both side surfaces of the rotor 1 duringbraking is made difficult to be transmitted to the caliper 2 a. Namely,the mutual slidability between the shim plates is made excellent duringbraking so that a large braking torque will not be applied to thecaliper 2 a.

Namely, in the case of this embodiment, since slight swinging anddisplacement of the caliper 2 a is allowed, if a large braking torque istransmitted to this caliper 2 a, the behavior of this caliper 2 a wouldlikely become unstable. In addition, since the area of abutment betweenthe outer peripheral surface of each of the guide pins 5 a, 5 a′, 5 b,and 5 c and each of the guide holes 6 a and 6 a′ (see FIGS. 1 to 3) isnarrow, if a large braking torque is transmitted to the caliper 2 aduring braking, the wear of the abutment portion would likely progress.Accordingly, in the case of this embodiment, the braking torque appliedto the pads 10 a and 10 b during braking is made difficult to betransmitted to the caliper 2 a by the following construction.

For this purpose, in the case of this embodiment, pressed-side shimplates 26 a and 26 b are respectively lined on the reverse surfaces ofthe back plates 11 making up the pads 10 a and 10 b. In addition,pressing-side shim plates 27 a and 27 b are respectively lined on thedistal end face of the piston 14 incorporated on the inner side of thecaliper 2 a and on the inner side surface of the claw portion 13 aprovided on the outer side end portion of the caliper 2 a. Further, oneof the pressed-side shim plates 26 a and 26 b and one of thepressing-side shim plates 27 a and 27 b are slidably abutted againsteach other. These shim plates 26 a, 26 b, 27 a, and 27 b are fabricatedof metal plates such as stainless steel plates or the like, and are eachprovided with a resilient retainer for retaining the member to be added.It should be noted that since the shapes of such shim plates 26 a, 26 b,27 a, and 27 b and the structure of fitting to the mating member aresimilar to those of the conventionally known shim plates as disclosed inthe patent documents 4 to 10, a detailed illustration and descriptionthereof will be omitted.

In the case of this embodiment, planar portions of the pressed-side shimplate 26 a lined on the back plate 11 of the inner pad 10 a and thepressing-side shim plate 27 a lined on the distal end face of the piston14 are abutted against each other displaceably in the planar direction.Also, planar portions of the pressed-side shim plate 26 b lined on theback plate 11 of the outer pad 10 b and the pressing-side shim plate 27b lined on the inner side surface of the claw portion 13 a are abuttedagainst each other displaceably in the planar direction. It should benoted that, preferably, grease is applied between the planar portionswhich are abutted against each other in each of these combinations, or afilm made of a material having a low coefficient of friction, such aspolyamide resin, polytetrafluoroethylene, or the like, is formed on oneor both of the abutment surfaces of the planar portions.

In the case of this embodiment, by providing the above-described shimplates 26 a, 26 b, 27 a, and 27 b, the braking torque applied to thepads 10 a and 10 b during braking can be made difficult to betransmitted to the caliper 2 a. Namely, the braking torque applied tothe pads 10 a and 10 b during braking is borne by the support member 3 a(see FIG. 1) supporting the pads 10 a and 10 b. However, part of thisbraking torque is transmitted to the caliper 2 a through the piston 14and the claw portion 13 a. When the braking torque transmitted to thecaliper 2 a becomes large in this way, the degree to which the behaviorof the caliper 2 a becomes unstable during braking becomes noticeable,and the abutment wear of the outer peripheral surface of each of theguide pins 5 a, 5 a′, 5 b, and 5 c and each of the guide holes 6 a and 6a′ is likely to progress, as described before. In contrast, in the caseof this embodiment, as the abutment surfaces of the planar portions ofthe shim plates 26 a, 26 b, 27 a, and 27 b slide, the braking torque ismade difficult to be transmitted to the caliper 2 a. For this reason, itis possible to suppress progress in the uneven wear of the linings 15and the wear of the outer peripheral surfaces of the guide pins 5 a, 5a′, 5 b, and 5 c and the inner peripheral surfaces of the guide holes 6a and 6 a′. Further, the caliper 2 a and the pads 10 a and 10 b becomeeasily movable, so that an effect is produced in that it is possible tosuppress noise and judder occurring during braking.

Furthermore, in the case of this embodiment, the guide pins 5 a, 5 a′, 5b, and 5 c respectively have, at their opposite end portions in theaxial direction of the rotor 1, the small-diameter portions 28 a and 28b, 28 a′ and 28 b′, each having a clearance of a predetermined dimensionor more with respect to each of the guide holes 6 a and 6 a′ in whichthese guide pins 5 a, 5 a′, 5 b, and 5 c are fitted. In addition, theguide pins 5 a, 5 a′, 5 b, and 5 c respectively have, in theirintermediate portion in the axial direction of the rotor 1, thelarge-diameter portions 20 a, 20 b, 20 c, and 20 a′ whose diameters arelarger than the small-diameter portions 28 a and 28 b, 28 a′ and 28 b′.For this reason, it is possible to make much smaller the moment actingupon this caliper 2 a as a whole on the basis of the forces applied tothe caliper 2 a from the rotor 1 during braking, and it is possible tomore effectively suppress this caliper 2 a from tilting with respect tothe planar direction of the rotor 1. As a result, it is possible to moreeffectively suppress the occurrence of uneven wear in the linings 15 ofthe pads 10 a and 10 b, and more effectively suppress the brake noiseand judder occurring during braking.

Referring next to FIGS. 8 and 9, a detailed description will be given ofthe reason why the occurrence of uneven wear of the linings 15 can besuppressed in the above-described manner. First, FIG. 8 shows thestructure in which the respective guide pins 5 and the respective guideholes 6 which are fitted in these guide pins 5 are engaged with eachother axially displaceably, in the same way as the conventionalstructure shown in FIGS. 21 and 22 referred to above. The pressed-sideshim plates 26 a and 26 b and the pressing-side shim plates 27 a and 27b, which are similar to those of this embodiment, are retained by therespective mating members to be lined on, by means of unillustratedretainers, between the inner side surface of the claw portion 13 a ofthe caliper 2 a and the reverse surface of the back plate 11 of theouter pad 10 b and between the distal end face of the piston 14 and thereverse surface of the back plate 11 of the inner pad 10 a. Such astructure shown in FIG. 8 also falls within the technical scope of theinvention. In the case of such a structure shown in FIG. 8, it isreadily possible to make sufficiently small the frictional force actingbetween each pair of the pressed- and pressing-side shim plates 26 a, 26b, 27 a, and 27 b. For this reason, it is possible to make sufficientlysmall moments M₁′ and M₂′ based on forces acting upon the claw portion13 a and the piston 14 through the pads 10 a and 10 b from the rotor 1during braking. Accordingly, the caliper 2 a can be made difficult totilt with respect to the planar direction of the rotor 1 during braking,so that it is possible to suppress the occurrence of uneven wear in thepads 10 a and 10 b. In particular, due to the fact that the lengthbetween the claw portion 13 a and the center of the tilt in the casewhere the caliper 2 a tends to tilt with respect to the planar directionof the rotor 1 is large, the moment M₁′ acting upon this claw portion 13a becomes greater than the moment M₂′ acting upon the piston 14. Forthis reason, the effect of making it possible to suppress the tilting ofthe caliper 2 a by providing the pressed- and pressing-side shim plates26 b and 27 b on the inner side surface of the claw portion 13 a and thereverse surface of the back plate 11 of the outer pad 10 b is morenoticeable than the effect obtained by providing the pressed-side andpressing-side shim plates 26 a and 27 a on the distal end face of thepiston 14 and the reverse surface of the back plate 11 of the inner pad10 a.

In addition, in the case of the structure shown in FIG. 8, thepressed-side shim plates 26 a and 26 b are respectively retained byretainers on the back plates 11 of the pads 10 a and 10 b, and thepressing-side shim plates 27 a and 27 b are respectively retained byretainers on the claw portion 13 a and the piston 14. Therefore, therelative displacement in the planar direction of the mating members ofthe pressed-side and pressing-side shim plates 26 a, 26 b, 27 a, and 27b is not restricted. For this reason, the mating members of these shimplates 26 a, 26 b, 27 a, and 27 b become easily movable, and the momentsM₁′ and M₂′ acting upon the claw portion 13 a and the piston 14 duringbraking can be effectively made small, making it possible to effectivelyobtain the effect of preventing the tilting of the caliper 2 a. As aresult, according to the structure shown in FIG. 8, it is possible tomore effectively suppress the occurrence of uneven wear in the linings15 of the pads 10 a and 10 b, and more effectively suppress the brakenoise and judder occurring during braking. In contrast to such astructure shown in FIG. 8, in the case of the structure disclosed in thepatent document 7, the shim plates are respectively attached to thedistal end face of the piston and the reverse surface of the back plateof the inner pad, but the shim plates are not installed on the clawportion and the reverse surface of the back plate of the outer pad. Inthe case of such a structure disclosed in the patent document 7, theeffect of suppressing the tilting of the caliper is substantially lowerthan the case of the invention for the above-described reasons.

Furthermore, in the case of this embodiment shown in FIGS. 5 to 7, thefollowing effect is obtained in addition to the effects obtained by theabove-described structure shown in FIG. 8. Namely, in the case of thisembodiment, as illustrated in detail in FIG. 9, each guide pin 5 e has,at its opposite end portions in the axial direction of the rotor 1, thesmall-diameter portions 28 a and 28 b each having a clearance of apredetermined dimension or more with respect to the guide hole 6 a inwhich the guide pin 5 e is fitted. In addition, each guide pin 5 e has,in its intermediate portion in the axial direction of the rotor 1, alarge-diameter portion 20 d whose diameter is larger than those of thesmall-diameter portions 28 a and 28 b. For this reason, the engagingportion o between the guide hole 6 and the guide pin 5 can be positionedbetween, on the one hand, a sliding interface between the inner sidesurface of the claw portion 13 a and the outer pressing-side shim plate27 b and, on the other hand, a sliding interface between the distal endface of the piston 14 and the inner pressing-side shim plate 27 a withrespect to the axial direction of the rotor 1. During braking, thisengaging portion o serves as a rotational center of the moment M₁ actingupon the claw portion 13 a on the basis of the force applied from therotor 1 to the claw portion 13 a through the outer pad 10 b and thepressed- and pressing-side shim plates 26 b and 27 b, and also serves asa rotational center of the moment M₂ acting upon the piston 14 on thebasis of the force applied from the rotor 1 to the piston 14 through theinner pad 10 a and the pressed- and pressing-side shim plates 26 a and27 a. For this reason, the moments M₁ and M₂ act in mutually oppositedirections and act in such a manner as to offset each other duringbraking, thereby making it possible to make smaller the moment actingupon the caliper 2 a as a whole. Thus, it is possible to moreeffectively obtain the effect of preventing the tilting of the caliper 2a. As a result, it is possible to more effectively suppress theoccurrence of uneven wear in the linings 15 of the pads 10 a and 10 b,and more effectively suppress the brake noise and judder occurringduring braking.

It should be noted that FIG. 9 shows the moments M₁ and M₂ acting uponthe caliper 2 a as well as their rotational center o in the case wherethe overall shape of the generating line of the large-diameter portion20 d formed in the axial intermediate portion of the guide pin 5 e is aconvex circular arc. However, also in the case where the large-diameterportion of the guide pin 5 e is arranged such that the shape of thegenerating line of the intermediate portion is made rectilinear, asshown in FIGS. 2(a) to 2(c) referred to above, the engaging portionbetween the guide pin 5 e and the guide hole 6 e can be easilypositioned between, on the one hand, the sliding interface between theinner side surface of the claw portion 13 a and the outer pressing-sideshim plate 27 b and, on the other hand, the sliding interface betweenthe distal end face of the piston 14 and the inner pressing-side shimplate 27 a. According to the structure in which each guide pin 5 e has,at its opposite end portions in the axial direction of the rotor 1, thesmall-diameter portions 28 a and 28 b each having a clearance of apredetermined dimension or more with respect to the guide hole 6 a inwhich the guide pin 5 e is fitted, and has, in its intermediate portionin the axial direction of the rotor 1, the large-diameter portion 20 dwhose diameter is larger than those of the small-diameter portions 28 aand 28 b, it is possible to make small the moment acting upon thecaliper 2 a as a whole during braking. In addition, it is possible tomore effectively obtain the effect of preventing the tilting of thecaliper.

Since the other arrangements and action concerning the first embodimentare similar to those of the first reference example shown in FIGS. 1 to3 referred to above, a redundant description thereof will be omitted.

Next, a description will be given of an experiment which was conductedto confirm the effects obtained by the structure shown in FIGS. 5 to 8referred to above. The experiment was conducted by using five types offloating caliper type disc brakes including implemented products 1 and 2belonging to the invention and comparative products 1 to 3 deviatingfrom the invention. The specifications of these five types are shown inTable 1 below. Namely, an implemented product 1 has a structure similarto that shown in FIG. 8, and has pressing- and pressed-side shim plates26 a and 26 b, 27 a and 27 b, respectively, on both inner and outersides with respect to the rotor 1. In addition, an implemented product 2has a structure similar to that of the first embodiment shown in FIGS. 5to 7, and is provided with the large-diameter portions 20 a and 20 a′ inthe intermediate portions of the guide pins 5 a and 5 a′, as well as thesmall-diameter portions 28 a and 28 b, 28 a′ and 28 b′, on their bothsides, respectively, in addition to the structure of the implementedproduct 1. In addition, the comparative product 1 has the conventionalstructure shown in FIGS. 21 and 22 referred to above, and the shimplates are installed only on the reverse surfaces of the back plates 11of the pads 10 a and 10 b, and the shim plates are not installed on theinner side surface of the claw portion 13 a and the distal end face ofthe piston 14. In addition, the comparative product 2 has a structuresimilar to that disclosed in the patent document 7. Namely, thepressing- and pressed-side shim plates are installed only on the reversesurface of the back plate 11 of the inner pad 10 a and the distal endface of the piston 14. In addition, in the comparative product 3, thepressing- and pressed-side shim plates are installed only on the reversesurface of the back plate 11 of the outer pad 10 b and the inner sidesurface of the claw portion 13 a. TABLE 1 Large-diameter Portion +Small-diameter Portions of Shim Plate Guide Pin Implemented Pressing-and pressed-side absent Product 1 shim plates are present on both innerand outer sides. Implemented ditto present Product 2 Comparative Shimplates are present on absent Product 1 the pad side on both the innerand outer sides Comparative Pressing- and pressed-side ditto Product 2shim plates are present only on the inner side. Comparative Pressing-and pressed-side ditto Product 3 shim plates are present only on theouter side.

In addition, by using these implemented products 1 and 2 and comparativeproducts 1 to 3, the tilting angle of the center axis of the caliper 2 aduring braking was measured in a state in which the oil pressure(braking fluid oil) of pressure oil fed into a cylinder portion 12 wasmade different variously. FIG. 10 shows the results of the experimentthus conducted. It should be noted that, in FIG. 10, solid lines a and brespectively show the implemented products 1 and 2, and dotted lines cto e respectively show the comparative products 1 to 3.

As is apparent from the results of the experiment shown in FIG. 10, inthe case of the implemented product 1 in which the pressed-side shimplates 26 a and 26 b and the pressing-side shim plates 27 a and 27 b arerespectively provided on both inner and outer sides with respect to therotor 1, it was possible to make the tilt angle of the caliper 2 aduring braking sufficiently small to about 50% of the cases of thecomparative products 1 and 2. In addition, in the case of theimplemented product 2 in which the guide pins 5 a, 5 b, 5 c, and 5 a′respectively have the large-diameter portions 20 a, 20 b, 20 c, and 20a′ in their intermediate portions, as well as the small-diameterportions 28 a, 28 a′, 28 b, and 28 b′, and a clearance of apredetermined dimension or more is provided between each of thesesmall-diameter portions 28 a, 28 a′, 28 b, and 28 b′ and each of theguide holes 6 a and 6 a′, it was possible to make the tilt angle of thecaliper 2 a during braking much smaller than in the case of theimplemented product 1.

Second Embodiment

Next, FIGS. 11 to 13 show a second embodiment of the invention. In thecase of this embodiment, four retainers 30 are formed in a centralportion of the inner pressing-side shim plate 27 a in such a manner asto project toward the piston 14 side (the right-hand side in FIG. 11) bybending inner sides of U-shaped cutouts. These retainers 30 are retainedat the inner side of the opening end portion of the piston 14. Inaddition, one outside diameter-side retainer 31 and a pair of insidediameter-side retainers 32 are respectively formed at an outsidediameter-side peripheral edge of the inner pressed-side shim plate 26 aand an inside diameter-side peripheral edge thereof in such a manner asto be bent toward the back plate 11 side (the left-hand side in FIG. 11)of the inner pad 10 a. The outside diameter- and inside diameter-sideretainers 31 and 32 are retained in retaining grooves 33 a and 33 bwhich are respectively formed in an outside diameter-side peripheraledge and an inside diameter-side peripheral edge of the back plate 11.By virtue of this arrangement, the displacement of the innerpressed-side shim plate 26 a is restricted in the radial andcircumferential directions of the rotor 1 (see FIG. 1, among others)with respect to the inner pad 10 a.

In addition, in the case of this embodiment, two retainers 34 are formedin a central portion of the outer pressing-side shim plate 27 b in sucha manner as to project toward the claw portion 13 a side (the right-handside in FIG. 12) by bending inner sides of U-shaped cutouts. Theseretainers 34 are retained at the inner side of a recess 35 provided in acentral portion of this claw portion 13 a. The interval between a pairof pressing pieces 36 making up this claw portion 13 a for pressing theouter pad 10 b toward the rotor 1 becomes smaller (narrower) as shown inFIG. 13. For this reason, by making an interval L₃₄ between theretainers 34 larger than an interval L₃₆ between distal ends of thesepressing pieces 36 (L₃₄>L₃₆), it is possible to prevent thepressing-side shim plate 27 b from becoming displaced downwardly inFIGS. 12 and 13 with respect to the claw portion 13 a. Meanwhile, anoutside diameter-side retainer 31 and inside diameter-side retainers 32,which are similar to those of the inner pressed-side shim plate 26 a,are respectively formed at an outside diameter-side peripheral edge ofthe outer pressed-side shim plate 26 b and an inside diameter-sideperipheral edge thereof. The outside diameter- and inside diameter-sideretainers 31 and 32 are retained in retaining grooves 33 a and 33 bwhich are respectively formed in an outside diameter-side peripheraledge and an inside diameter-side peripheral edge of the back plate 11 ofthe outer pad 10 b. By virtue of this arrangement, the displacement ofthe outer pressed-side shim plate 26 b in the radial and circumferentialdirections of the rotor 1 with respect to the outer pad 10 b isrestricted.

In addition, the pressed- and pressing-side shim plates 26 a, 26 b, 27a, and 27 b are fabricated of metal plates such as stainless steelplates or the like. A rubber coating is provided on a side surface ofthe inner pressing-side shim plate 27 a opposing the piston 14 and on aside surface of the outer pressing-side shim plate 27 b opposing theclaw portion 13 a, respectively. Furthermore, a fluoro coating isprovided both on that side surface of both side surfaces of the innerpressed-side shim plate 26 a which is in sliding contact with the innerpressing-side shim plate 27 a and on that side surface of both sidesurfaces of the outer pressed-side shim plate 26 b which is in slidingcontact with the outer pressing-side shim plate 27 a.

In the case of this embodiment constructed as described above, as theside surfaces are provided with a rubber coating or a fluoro coating,the pressed- and pressing-side shim plates 27 a, 27 b, 26 a, and 26 bcan be made relatively displaceable more easily during braking, and thegeneration of abnormal noise can be suppressed more effectively.

Since the other arrangements and action are similar to those of thefirst embodiment shown in FIGS. 5 to 7 referred to above, identicalportions will be denoted by the same reference numerals, and a redundantdescription thereof will be omitted.

It should be noted that the invention is not limited to the structure ofthis embodiment, and both inner and outer pressed- and pressing shimplates 26 a, 27 a, 26 b, and 27 b may be fabricated of mere metal platessuch as stainless steel plates or the like without being provided withthe rubber coating or the fluoro coating.

In addition, in the structure of the first embodiment shown in FIGS. 5to 7 referred to above or the second embodiment shown in FIGS. 11 to 13,although not shown, a bent piece, which is bent toward the outer pad 10b side and is not retained by any member in an ordinary state, may beprovided at the outer diameter-side peripheral edge of the outerpressing-side shim plate 27 b. In the case where such a bent piece isprovided, as this bent piece is retained by an upper edge of the outerpad 10 b or the outer pressed-side shim plate 26 b, it is possible torestrict the displacement of the outer pressing-side shim plate 27 b ina direction toward the center of the rotor 1 (downwardly in FIGS. 12 and13). In addition, a bent piece, which is not shown but is bent in adirection away from the rotor 1 (see FIG. 5, among others) side, may beprovided at the inner periphery-side peripheral edge of the innerpressed-side shim plate 26 a. In this case, as the inner pressing-sideshim plate 27 a is retained by this bent piece, it is possible torestrict the displacement of the inner pressing-side shim plate 27 a ina direction toward the center of the rotor 1 (downwardly in FIG. 11).

In addition, in the structure of the first embodiment shown in FIGS. 5to 7 referred to above or the second embodiment shown in FIGS. 11 to 13,although not shown, a shim plate with a rubber coating provided on bothsides may be clamped in at least one interval between each of the pads10 a and 10 b and each of the pressed-side shim plates 26 a and 26 b andbetween each of the distal end face of the piston 14 and the inner sidesurface of the claw portion 13 a and each of the pressing-side shimplates 27 a and 27 b, so as to suppress the generation of abnormal noiseduring braking more effectively. In addition, a shim plate with aheat-insulating resin coating provided on both sides may be clamped inat least one interval between each of the pads 10 a and 10 b and each ofthe pressed-side shim plates 26 a and 226 b and between each of thedistal end face of the piston 14 and the inner side surface of the clawportion 13 a and each of the pressing-side shim plates 27 a and 27 b, soas to suppress the heat generated between the rotor 1 and the pads 10 aand 10 b during braking from being transmitted to the caliper 2 a.

Third Embodiment

Next, FIG. 14 shows a third embodiment of the invention. In the case ofthis embodiment, in the structure of the second embodiment shown inFIGS. 11 to 13 referred to above, a pair of retaining protrusions 41each having a circular cross section are provided in both end portionsin the widthwise direction (the left-and-right direction in FIG. 14) ofthe outer pressing-side shim plate 27 b, and are formed (built up) insuch a manner as to project toward the claw portion 13 a side. Inaddition, a pair of retaining holes 42 each having a circular crosssection are provided in inner surfaces (obverse surfaces in FIG. 14) ofthe pair of pressing pieces 36 making up this claw portion 13 a. Ends ofthese retaining holes 42 which are located away from the rotor side mayor may not be penetrated through outer surfaces (rear surfaces) of thepressing pieces 36. The retaining protrusions 41 are retained by theretaining holes 42 by being press fit into the retaining holes 42. Byvirtue of this arrangement, the pressing-side shim plate 27 b isrestricted from moving dislocatedly with respect to the claw portion 13a in the planar direction of this pressing-side shim plate 27 b.

Since the other arrangements and action are similar to those of thesecond embodiment shown in FIGS. 11 to 13 referred to above, identicalportions will be denoted by the same reference numerals, and a redundantdescription thereof will be omitted.

Fourth Embodiment

Next, FIG. 15 shows a fourth embodiment of the invention. In the case ofthis embodiment, in the structure of the second embodiment shown inFIGS. 11 to 13 referred to above, a retaining protrusion 43 having ahanging bell-shaped cross section is provided in a central portion ofthe outer pressing-side shim plate 27 b, and is formed (built up) insuch a manner as to project toward the claw portion 13 a side. Thisretaining protrusion 43 is press fit into an inner side of a recess 35formed in a central portion of the claw portion 13 a and is therebyretained by this claw portion 13 a. By virtue of this arrangement aswell, the pressing-side shim plate 27 b is restricted from movingdislocatedly with respect to the claw portion 13 a in the planardirection of this pressing-side shim plate 27 b.

Since the other arrangements and action are similar to those of thesecond embodiment shown in FIGS. 11 to 13 referred to above, identicalportions will be denoted by the same reference numerals, and a redundantdescription thereof will be omitted.

It should be noted that the retaining protrusion 43 for being retainedby the inner side of the recess 35 of the claw portion 13 a is notlimited to the shape shown in FIG. 15, and a retaining protrusion 43 amay, for example, have a substantially circular cross-sectional shape,as shown in FIG. 16.

Fifth Embodiment

Next, FIG. 17 shows a fifth embodiment of the invention. In the case ofthis embodiment, in the structure of the second embodiment shown inFIGS. 11 to 13 referred to above, a pair of retaining protrusions 44each having a circular cross section are provided in both end portionsin the widthwise direction (the left-and-right direction in FIG. 17) ofthe inner pressing-side shim plate 27 a, and are formed (built up) insuch a manner as to project toward the piston 14 side. These retainingprotrusions 44 are retained by the piston 14 by being press fit into theinner side of the circular opening of the piston 14. For this reason, inthe case of this embodiment, in a state before the retaining protrusions44 are press fit into the inner side of this piston 14, a length L₄₄between those portions of outer peripheral edges of the retainingprotrusions 44 which are located on the widthwise outermost sides in thepressing-side shim plate 27 a is set to be slightly greater than aninside diameter d₁₄ of the opening of the piston 14 (L₄₄>d₁₄). By virtueof this arrangement, the pressing-side shim plate 27 a is restrictedfrom moving dislocatedly with respect to the piston 14 in the planardirection of this pressing-side shim plate 27 a.

Since the other arrangements and action are similar to those of thesecond embodiment shown in FIGS. 11 to 13 referred to above, identicalportions will be denoted by the same reference numerals, and a redundantdescription thereof will be omitted.

Sixth Embodiment

Next, FIG. 18 shows a sixth embodiment of the invention. In the case ofthis embodiment, in the structure of the second embodiment shown inFIGS. 11 to 13 referred to above, a retaining protrusion 45 having asemicircular cross section is provided in a central portion of the innerpressing-side shim plate 27 a, and is formed (built up) in such a manneras to project toward the piston 14 side. This retaining protrusion 45 ispress fit into the inner side of the circular opening of the piston 14and is thereby retained by this piston 14. By virtue of this arrangementas well, the pressing-side shim plate 27 a is restricted from movingdislocatedly with respect to the piston 14 in the planar direction ofthis pressing-side shim plate 27 a.

Since the other arrangements and action are similar to those of thesecond embodiment shown in FIGS. 11 to 13 referred to above, identicalportions will be denoted by the same reference numerals, and a redundantdescription thereof will be omitted.

Seventh Embodiment

Next, FIGS. 19 and 20 show a seventh embodiment of the invention. In thecase of this embodiment, a curved portion 37 having a circulararc-shaped cross section is provided at an inside diameter-side end (alower end in FIGS. 19 and 20) of the outer pressing-side shim plate 27 bin such a manner as to be curved toward the claw portion 13 a side overthe entire length in the widthwise direction (in a directionperpendicular to the plane of the drawings in FIGS. 19 and 20). Inaddition, a cylindrical portion parallel to the center axis of the rotor1 is provided at a distal half portion of this curved portion 37. Inaddition, a bent piece 38 is provided at an outside diameter-side end ofthe pressing-side shim plate 27 b in such a manner as to be bent towardthe outer pad 10 b side over the entire length in the widthwisedirection. Even in the event that the outer pressing-side shim plate 27b tends to come off the claw portion 13 a toward the inside diameterside, this bent piece 38 functions to prevent it from occurring.Furthermore, inside diameter- and outside diameter-side curved portions39 and 40 each having a circular cross section are respectively providedat both inside diameter- and outside diameter-side ends of the innerpressing-side shim plate 27 a in such a manner as to be curved towardthe piston 14 side over the entire length in the widthwise direction (inthe direction perpendicular to the plane of the drawings in FIG. 19).The curved portion 37 provided on the outer pressing-side shim plate 27b and the inside diameter- and outside diameter-side curved portions 39and 40 provided on the inner pressing-side shim plate 27 a arerespectively opposed to one surfaces of the outer and inner pressed-sideshim plates 26 b and 26 a.

In the case of this embodiment constructed as described above, even incases where the caliper 2 a has been swung and displaced in thedirection shown by arrow B in FIG. 19 independently of the rotor 1 andthe pads 10 a and 10 b for some cause or other, the pressed- andpressing-side shim plates 26 a, 26 b, 27 a, and 27 b can be slidsmoothly with each other, making it possible to stably obtain a desiredbraking force. For example, in a case where the caliper 2 a has beenswung and displaced counterclockwise in FIGS. 19 and 20 relative to theouter and inner pads 10 b and 10 a, a pressing force can be impartedstably from the claw portion 13 a to the pressed-side shim plate 26 blined on the outer pad 10 b by means of the curved portion 37 providedon the outer pressing-side shim plate 27 b during braking. Likewise, apressing force can be imparted stably from the distal end face of thepiston 14 to the pressed-side shim plate 26 a lined on the inner pad 10a by means of the curved portion 40 provided on the inner pressing-sideshim plate 27 a. In addition, in a case where the caliper 2 a has beenswung and displaced clockwise in FIGS. 19 and 20 relative to the pads 10b and 10 a, a pressing force can be imparted stably from the piston 14to the pressed-side shim plate 26 a lined on the inner pad 1 a by meansof the inside diameter-side curved portion 39 provided on the innerpressing-side shim plate 27 a during braking. As a result, even in caseswhere the caliper 2 a has been swung and displaced, a desired brakingforce can be obtained stably. In addition, since the curved portion 37and the outside diameter- and inside diameter-side curved portions 40and 39 are provided, it becomes possible to make it easy for the outerand inner pressing-side shim plates 27 b and 27 a to satisfactorilyfollow the swinging motion and displacement of the caliper 2 airrespective of this swinging motion and displacement.

Since the other arrangements and action are similar to those of thefirst embodiment shown in FIGS. 5 to 7 referred to above, identicalportions will be denoted by the same reference numerals, and a redundantdescription thereof will be omitted.

It should be noted that although in the above-described embodiments andreference examples an illustration has been given of the case where twoguide pins are used, three or more guide pins may be used inimplementing the invention. In addition, the pressed-side shim plates 26a and 26 b and the pressing-side shim plates 27 a and 27 b may berespectively fixed to the surfaces of the back plates 11 of the pads 10a and 10 b which are located away from the rotor 1 side and to thepressing sides of the piston 14 and the claw portion 13 a by bonding orthe like.

As the above, the present invention is explained in detail and explainedreferring some specific embodiments, however, it will be apparent tothose skilled in the art that various modifications and variations canbe made to the preferred embodiments of the present invention withoutdeparting from the spirit or scope of the invention.

The present application is based on Japanese Patent Application(P.2003-099949) filed on Apr. 3, 2003 and Japanese Patent Application(P.2004-071419) filed on Mar. 12, 2004, the contents of which areincorporated herein by reference.

INDUSTRIAL APPLICABILITY

In the case of the floating caliper type disk brake of the inventionconstructed as described above, the pressed-side shim plate and thepressing-side shim plate are present both between the claw portion andthat surface of one of the pair of pads which is located away from therotor side and between the piston and that surface of the other padwhich is located away from the rotor side, and these shim plates areslidably abutted against each other. For this reason, the frictionalforce acting between one surfaces of both these shim plates can beeasily made sufficiently small. For this reason, it is possible to makesufficiently small the moments based on the forces applied to the clawportion and the piston from the rotor through the pads during braking,and the caliper can be difficult to tilt with respect to the planardirection of the rotor during braking. As a result it is possible tosuppress the occurrence of uneven wear in the pads. In addition, in thecase of the invention, the pressed-side shim plates are respectivelyfixed to or retained by the back plates, and the pressing-side shimplates are respectively fixed to or retained by the pressing sides ofthe claw portion and the piston. For this reason, the relativedisplacement of these pressed- and pressing-side shim plates in theplanar direction is not restricted. For this reason, both these shimplates are easily movable, and the moments acting upon the claw portionand the piston during braking can be effectively made small, therebymaking it possible to effectively obtain the effect of preventing thetilting of the caliper. As a result, according to the invention, it ispossible to more effectively suppress the occurrence of uneven wear inthe pads, and effectively suppress the occurrence of brake noise andjudder during braking.

1. A floating caliper type disc brake comprising: a support member fixedto a vehicle body and disposed adjacent to a rotor which rotatestogether with a wheel; a pair of pads supported by the support member onboth sides of the rotor slidably in an axial direction thereof; acaliper supported displaceably in the axial direction of the rotor, thecaliper being supported by a plurality of guide holes provided in thesupport member and a plurality of guide pins respectively fitted in theguide holes; a claw portion provided on one side of a bridge portion ofthe caliper, the bridge portion straddling the rotor; and a pistonprovided on another side thereof, wherein the pair of pads are pressedagainst both side surfaces of the rotor in consequence of the extensionof the piston so as to effect braking, pressed-side shim plates arerespectively retained by those surfaces of back plates of the pair ofpads which are located away from a rotor side, pressing-side shim platesare respectively retained by pressing sides of the claw portion and thepiston, and each of the pressed-side shim plates and each of thepressing-side shim plates are slidably abutted against each other. 2.The floating caliper type disc brake according to claim 1, wherein eachof the plurality of guide pins comprises, at its each opposite endportion in the axial direction of the rotor, a first diameter portionhaving a clearance of a predetermined dimension or more with respect tothe guide hole in which the guide pin is fitted, and at least one of theguide pins comprises, in its intermediate portion in the axial directionof the rotor, a second diameter portion whose diameter is larger thanthat of the first diameter portion.
 3. The floating caliper type discbrake according to claim 2, wherein, of the plurality of guide pins, oneguide pin other than the guide pin having the second diameter portioncomprises, in its intermediate portion in the axial direction of therotor, a third diameter portion whose diameter is larger than that ofthe first diameter portion.
 4. The floating caliper type disc brakeaccording to claim 2, wherein, of the plurality of guide pins, the oneguide pin other than the guide pin having the second diameter portioncomprises a fourth diameter portion connecting the first diameterportions and extending in the axial direction of the rotor with aclearance of a predetermined dimension or more with respect to an innerperipheral surface of the guide hole.
 5. The floating caliper type discbrake according to claim 2, wherein a shape of a generating line of thesecond diameter portion or the third diameter portion having the largediameter is one of a convex circular arc, a shape in which a rectilinearportion is sandwiched by a pair of convex circular arcs, and atrapezoid.
 6. The floating caliper type disc brake according to claim 2,wherein the second diameter portion or the third diameter portion havingthe large diameter is formed integrally with the guide pin.
 7. Thefloating caliper type disc brake according to claim 2, wherein thesecond diameter portion or the third diameter portion having the largediameter is formed as a sleeve is fitted over and fixed to the guidepin.
 8. The floating caliper type disc brake according to claim 2,wherein a ring of an elastic material is fitted over each of axiallyopposite sides of the guide pin sandwiching the second diameter portionor the third diameter portion having the large diameter.
 9. A floatingcaliper type disc brake comprising: a support member fixed to a vehiclebody and disposed adjacent to a rotor which rotates together with awheel; a pair of pads supported by the support member on both sides ofthe rotor slidably in an axial direction thereof; a caliper supporteddisplaceably in the axial direction of the rotor, the caliper beingsupported by a plurality of guide holes provided in the support memberand a plurality of guide pins respectively fitted in the guide holes; aclaw portion provided on one side of a bridge portion of the caliper,the bridge portion straddling the rotor; and a piston provided onanother side thereof, wherein the pair of pads are pressed against bothside surfaces of the rotor in consequence of the extension of the pistonso as to effect braking, pressed-side shim plates are respectively fixedto or retained by those surfaces of back plates of the pair of padswhich are located away from a rotor side, pressing-side shim plates arerespectively fixed to or retained by pressing sides of the claw portionand the piston, and each of the pressed-side shim plates and each of thepressing-side shim plates are slidably abutted against each other. 10.The floating caliper type disc brake according to claim 9, wherein eachof the plurality of guide pins comprises, at its each opposite endportion in the axial direction of the rotor, a first diameter portionhaving a clearance of a predetermined dimension or more with respect tothe guide hole in which the guide pin is fitted, and at least one of theguide pins comprises, in its intermediate portion in the axial directionof the rotor, a second diameter portion whose diameter is larger thanthat of the first diameter portion.
 11. The floating caliper type discbrake according to claim 10, wherein, of the plurality of guide pins,one guide pin other than the guide pin having the second diameterportion comprises, in its intermediate portion in the axial direction ofthe rotor, a third diameter portion whose diameter is larger than thatof the first diameter portion.
 12. The floating caliper type disc brakeaccording to claim 10, wherein, of the plurality of guide pins, oneguide pin other than the guide pin having the second diameter portioncomprises a fourth diameter portion connecting the first diameterportions and extending in the axial direction of the rotor with aclearance of a predetermined dimension or more with respect to an innerperipheral surface of the guide hole.
 13. The floating caliper type discbrake according to claim 10, wherein a shape of a generating line of thesecond diameter portion or the third diameter portion having the largediameter is one of a convex circular arc, a shape in which a rectilinearportion is sandwiched by a pair of convex circular arcs, and atrapezoid.
 14. The floating caliper type disc brake according to claim10, wherein the second diameter portion or the third diameter portionhaving the large diameter is formed integrally with the guide pin. 15.The floating caliper type disc brake according to claim 10, wherein thesecond diameter portion or the third diameter portion having the largediameter is formed as a sleeve is fitted over and fixed to the guidepin.
 16. The floating caliper type disc brake according to claim 10,wherein a ring of an elastic material is fitted over each of axiallyopposite sides of the guide pin sandwiching the second diameter portionor the third diameter portion having the large diameter.
 17. Thefloating caliper type disc brake according to claim 10, wherein a curvedportion having a circular arc-shaped cross section and curved toward aside of the claw portion or the piston is provided at an end of at leastone of the pressing-side shim plates so as to retain or fix thepressing-side shim plate, the curved portion being opposed to onesurface of the pressed-side shim plate.
 18. The floating caliper typedisc brake according to claim 1, wherein a curved portion having acircular arc-shaped cross section and curved toward a side of the clawportion or the piston is provided at an end of at least one of thepressing-side shim plates so as to retain or fix the pressing-side shimplate, the curved portion being opposed to one surface of thepressed-side shim plate.